The present disclosure relates to methods and apparatuses for forming classified catalyst compositions and further relates to a polyolefin composition produced with the classified catalyst composition.
Polymerization catalysts, such as Ziegler-Natta polymerization catalysts, include a procatalyst in particulate or granular form. These procatalysts often contain some amount of small particles known as fines. The presence of fines is problematic as fines produce small polymer particles during the polymerization process. The small polymer particles cause dusting and plugging of production equipment during polymer production. Catalyst fines further contribute to manufacturing difficulties such as fouling and other problems.
Conventional approaches to fines removal from procatalysts include elutriation, sedimentation, and wet sieving. These approaches, however, have significant drawbacks including high cost, inefficient operation, and the inability to precisely size the catalyst particles. Such drawbacks become worse when the particles are fragile or have mutual attraction. Desirable would be a fines removal process yielding a classified catalyst composition containing a small amount of catalyst fines.